Bottle inspection machine

ABSTRACT

An inspection machine for transilluminatable bottles inspects the sidewalls of bottles by transmitting a diffused beam of light through the sidewall and using a plurality of mirrors appropriately arranged for detecting or recording the images emergent from the bottle in different directions in the same image recording camera. The arrangement requires at least two separate beam paths and mirrors in each path directing the bottle emergent beams to the camera while the bottles are being conveyed through a position in which they are illuminated. In an improved arrangement, there is a separate cooperating series of beam deflecting mirrors which generate at least three independent beam paths that impinge from different directions on the sidewall of the bottle being inspected. The recording device is preferably a camera having a charge coupled device image plate.

BACKGROUND OF THE INVENTION

The invention disclosed herein pertains to a machine for inspectingbottles or the like through which light can be transmitted.

In beverage bottling lines inspection machines are used to detect andeliminate damaged or dirty bottles before they reach a bottle fillingmachine. Most pre-existing bottle filling machines require rotation ofeach bottle about its vertical axis while a thin vertically extensivelight beam passes through the bottle for a projected image of the bottlesidewalls to be recorded. During rotation, substantially only the centerof the bottle is currently recorded along a vertical line. A line scancamera may be used. The image of the bottle sidewall obtained is ofsufficient quality to reveal or detect bottles that are damaged ordirty. In the pre-existing machine just outlined, rotation of thebottles as they arrive in the inspection zone requires that the bottlesbe mounted on rotationally driven plates that are carried on a carouselthat has the mechanism for rotating the plates. This is a complicatedand expensive structural arrangement which it would be desirable toavoid.

There is existing inspection apparatus which does not require rotationof the bottle during image recording of the sidewall as is disclosed inGerman specification DE-AS 26 17 457. In the patented apparatus, thesidewall region of the bottle is recorded by only one camera that viewsthe bottle from different directions. This bottle inspection apparatusis of comparatively simple design but is subject to causing opticaldistortions due to the surface curvature of the bottles. With thisarrangement, evaluation of the image for the presence of dirt or damageis difficult and uncertain.

SUMMARY OF THE INVENTION

The invention disclosed herein is an improvement over the inspectionapparatus outlined in the preceding paragraphs. According to theinvention, a machine for inspecting the sidewall of bottles or the likeis achieved and implemented at comparatively low cost although theresulting images of the bottles are of good quality.

The improved bottle inspection apparatus uses an arrangement of mirrorswhich direct a plurality of individual beam paths that emerge from thesidewall region of a bottle that is transilluminated over its entirewidth through an image recording device such as a camera that has acharge coupled device (CCD) image plate. The arrangement ensures thatthe images projected to the camera by the individual beam paths are ofidentical size such that difficulties in image interpretation orevaluation are eliminated. The bottle wall inspection station can alsobe associated, in accordance with the invention, with an additionalimage recording device, such as another CCD camera, for checking thecontour, type or color of the bottles that traverse the secondinspection station. The second image recording device can be positionedso that its beam path intersects the beam paths of the sidewallinspection arrangement such that recording of both images canadvantageously be triggered with only one camera triggering device.

How all of the foregoing general features and other more specificfeatures of the invention are achieved and implemented will appear inthe more detailed description of a preferred embodiment of the inventionwhich will now be set forth in reference to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic top plan view of a machine for inspectingbottles wherein the new sidewall inspection apparatus is used;

FIG. 2 is an enlarged representation of the bottle sidewall inspectionapparatus that is shown in more demagnified form in FIG. 1;

FIG. 3 is a diagrammatic side elevational view of one of the beam pathsextending from a luminescent screen to a camera that is depicted inreduced size in FIG. 1;

FIG. 4 is a diagrammatic side elevational view of another one of thebeam paths that is present in FIG. 2 as viewed in the direction in whichthe bottles are conveyed;

FIG. 5 is a third diagrammatic side elevational view of another of thebeam paths present in FIG. 2 as viewed in the direction of bottleconveyance;

FIG. 6 is a schematic top plan view of an optical system that performsthe functions of the FIGS. 1-5 embodiment generally but has the mirrorsused in the optical system arranged differently from their arrangementin FIG. 2; and

FIG. 7 is a diagrammatic plan view in which there are two inspectionstations of the bottle sidewall inspecting types used.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1, bottles 5 are conveyed to the inspection machine onan infeed conveyor 14 which is driven continuously. The bottles 5 aretransported in upright position on conveyor 14, the bottles being inabutting position at that time. Conveyor 14 may be a belt conveyor or aconveyor comprised as a series of plates that are linked together toform a closed loop. The bottles must be spaced from each other when theyarrive at the inspection station 1. Accordingly, a pair of angulatedguide rails guide bottles 5 onto a conveyor 4 which has a higher linearvelocity than conveyor 14 so that a uniform width space is developedbetween consecutive bottles when they are passing through inspectionstation 1 on conveyor belt 4. Inspection station 1 comprises aluminescent screen emitting diffused light, a camera 3 which records animage of the bottle and several mirrors disposed between conveyor belt 4and camera 3 for directing light beams which entrain the image of thebottle from the bottle to the camera 3. The beam paths are marked 6, 7and 8. Inspection station 1 includes a second camera 15 for detectingthe contour, height and/or color of the bottles being inspected. Thelength of the beam path from the bottle 5 being inspected to the cameracan be very short such as between 750 mm and 1500 mm. It has been founddesirable to use a combination of mirrors and optical properties of thecamera which provides for a beam path length of about 1240 mm.

Bottles that fail sidewall inspection or contour, height and/or colorinspection are automatically ejected by actuation of ejection device 31when any unacceptable bottle becomes aligned with ejection device 31. Acontainer 32 is provided for collecting unacceptable bottles which areejected. Ejector devices are well known and need not be described ingreat detail. Basically, the ejector device 31 is activated at the endof a time delay interval which allows the unacceptable bottle to travelthe distance from the inspection zone to the ejector device. Triggeringthe two cameras 3 and 15 and ejection device 31 occurs when a bottle 5cuts the light beam of a photodetector 33 which precedes inspectionstation 1 and which takes into account a delay interval whose lengthdepends on the speed of bottle conveyance.

A second inspection station, designated generally by the numeral 40, isarranged downstream from the ejector device. Second inspection station40 provides for inspecting the bottoms of the bottles. Bottom inspectionrequires that the bottom of the bottle be free of any supporting member.There is a gap between bottle feed conveyor 4 and output conveyor 45.The bottles are transported across this gap by endless belts 41 whichfrictionally engage the sidewall of a bottle and carry it though spacewith its bottom exposed. The bottles are released from friction belts 41to outfeed conveyor 45 after they have traversed the gap betweenconveyors 4 and 45. Another ejection device 46 is positioned as shown inFIG. 1 for ejecting bottles which have failed bottom inspection. Ejector46 ejects unacceptable containers into a collecting container 47. Thereis also a third ejection device 48 which shifts bottles which arepotentially reusable after repeated cleaning onto a conveyor 49 which isarranged parallel with the outfeed conveyor belt 45.

Attention is now invited to FIG. 2 which depicts an enlarged version ofinspection station 1. In FIG. 2, light emitted from diffuse light source2 penetrates from one side of bottle 5 through the bottle to define abeam 6 in which an image of the bottle is entrained. In other words, thewall of the bottle or any defects or contaminants in it modulate lightbeam 6. Another light beam 7 also entrains an image of the bottle. Thebeams or the beam paths are arranged symmetrically to the optical axis12 of camera 3. Thus, the mirrors 7a and 7b forming the beam path 7 arepositioned symmetrically to the mirrors 6a and 6b of the beam path 6.The two mirrors 6b and 7b are oriented with respect to each other suchthat the beam path 6 and 7 meet at a given angle, for example, 60°,relative to the center lines 6' and 7' of the beam paths in anintersecting region above conveyor belt 4. A third more centralized beampath directs the image that emerges from bottle 5 through the sequenceof reflecting mirrors 8c, 8b and 8a in that order to the optical axis 12of camera 3. In the third beam path, the center line or center axis 8'of third beam 8 bisects the angle between the two center axes 6' and 7'.Mirror 8c is positioned so that the perpendicular projection of centeraxis 8' in FIG. 2 is oriented on the common point of intersection 10 ofthe three axes 6', 7' and 8' normal to the line of symmetry 11 of thebottle 5 being inspected and also to the running duration of conveyorbelt 4.

Sidewall inspecting camera 3 is provided with an image plate not visiblecomprised of charge coupled devices (CCD) on which the imagestransmitted along the three beam paths 6, 7 and 8 are formed one next tothe other. There is an evaluation device, not shown, which under programcontrol reads and evaluates images recorded by camera 3. The evaluationprogram is preferably designed so that only the center image of eachbeam path is evaluated while the margin areas can be masked to someextent or can be ignored in order to avoid imprecisions in the marginareas of the recorded areas due to the optical distortions on thesharply curved bottle edges.

As previously mentioned, inspection station 1 includes a second camera15 for inspecting the contour and/or height and/or color of the bottlesto be inspected. Second camera 15 is disposed so that the beam path 16is not obstructed in whole or in part by any of the mirrors from thesidewall inspection device that utilize camera 3. Camera 15 interceptsan image of the bottle 5 which is presently positioned in theintersection region of the other beams 6, 7 and 8. In particular, theoptical axis 17 of camera 15 is oriented so that it extends to a commonpoint of intersection 10 with the three beam paths 6, 7 and 8 of thesidewall inspection beams. This arrangement permits operating the twocameras 3 and 15 with a common control signal for simultaneous imagerecording. It will be evident in FIG. 2 that camera 15 could be shiftedslightly to the left or to the right without the beam which the cameraintercepts being obstructed with any of the mirrors 6a, 8b or 8c. Adesirable arrangement is where the optical axis 17 of the camera 15 beampath 16 intersects the axis 8' or the optical axis 12 of camera 3 at anangle of approximately 25°.

Instead of the cameras 3 and 15 having their optical axes 12 and 17projected horizontally, the cameras can be arranged with their axesvertical and perpendicular to the plane in which the bottles areconveyed. To effectuate this arrangement, additional mirrors 13 and 18are required for bending the horizontal beam paths 7 and 8 for camera 3and beam path 16 for camera 15 so the image information beams can bereceived in the cameras along their vertically arranged axes.

In FIG. 3, for the sake of greater clarity, only the camera 3 and thetwo mirrors 7a and 7b in the beam path 7 are shown in a side view. Thebeam path of the center axis denoted by 7' is shown in FIG. 2.Positioning of the planar mirrors 7a and 7b (and also positioning of theremaining mirrors) takes place through two positioning plates marked 21and arranged parallel to each other and at a distance from each other ina horizontal plane. Plates 21 are fastened to and supported by spacerrods 22 from a base 19. Positioning plates 21 have slots correspondingto the thickness and width of the mirrors. The mirrors can be introducedfrom above through the slots with their lower edges resting on baseplate 19. This permits fast and simple exchange of mirrors if a mirroris damaged.

As shown in FIG. 3, the upper positioning plate 21 is fastened to aguide rod 20. In this figure, camera 3 is arranged with its optical axis12 vertically oriented. The camera 3 is pivotally connected by means ofa pin 36 to a clamping device 35 which allows the camera 3 to beadjusted up or down on rod 30. Clamping device 35 includes a pivotal pin36 which allows setting the angle of the optical axis of camera 3centrally of the mirror 13 which is arranged below the camera.

FIG. 4 is similar to FIG. 3 except that FIG. 4 depicts the mirrors 8a,8b, and 8c associated with the center beam path 8. As in the previousfigure, in FIG. 4 all remaining mirrors are omitted for the sake ofclarity.

FIG. 5 corresponds to FIG. 4 for the most part but with camera 15 andits beam path 16 involved in bottle contour and height detection beingadded. As previously indicated, because the optical axis of camera 15 isvertically oriented, mirror 18 is required for deflecting beam path 16from the perpendicular direction transversely to the line of symmetry 11of the bottle being inspected. The second camera 15, similarly to camera3, is fastened on the upper positioning plate 21 so as to be adjustable.

Inspection of the shoulder and head region of bottles 5 requires onlythat the upper region of the bottle be the source of an emergent lightbeam. This permits having beam path 17 of substantially shorter lengththan the beam paths for sidewall inspection so the camera 15 can bedisposed without an additional deflecting mirror as close to the bottleas the sidewall inspection camera 3.

FIG. 6 shows an alternative arrangement for the mirrors involved indirecting the modulated light beams emergent from bottle 5 for sidewallinspection. The depicted mirror configuration also defines two beampaths 6 and 7 disposed symmetrically to optical axis 12 of camera 3. Ofthese beam paths, only the central axis 6' and 7' are shown. For thispurpose, mirrors 6A, 6B and 7A and 7B are present which are disposed ata sufficient spacing from the optical axis 12 so that mirrors 8A, 8B and8C forming the third beam path 8 can be placed in front of the uppermirrors so the other two remaining beam paths so that a segment of thebeam path 8 leading to bottle 5 can pass with no obstruction between themirrors associated with beam paths 6 and 7. It should be understood thatthe plural beam paths discussed above are not necessarily limited tothree beam paths for sidewall inspection. It is conceivable andadvantageous to sometimes arrange additional mirrors for developing morethan three separate beam paths for sidewall inspection.

An elaboration of the bottle inspection machine discussed above isdepicted in the FIG. 7 diagrammatic top plan view of the machine. Thismachine uses a second inspection station 100 of the type used forsidewall inspection of bottles 5. Inspection station 100 is positionedadjacent outfeed conveyor 45 downstream from the inspection station 40wherein the bottom of each bottle is inspected. The mirror arrangementin inspection station 100 is the same as the arrangement of the mirrorsin inspection station 1. Bottle gripping closed loop belts 41 are drivensynchronously with conveyor belts 4 and 45. However, one of the closedloop belts 41 translates at a speed that differs by a small amount fromthe other belt 41. As a result of the difference in speeds, bottlesgripped by the belts are rotated about their vertical axes duringtransfer from conveyer belt 4 to conveyor belt 45. The angle of rotationis predetermined by the difference in belt speeds but the speeddifference is preferably chosen so that each bottle is rotated about 90°about its vertical axis without being tilted. Elimination of unusable orrejected bottles 5 is achieved using a conventional ejector such as wasused in FIG. 1 embodiment.

As stated, the speed difference between the two belts 41 is adjustableso that when converting the inspection machine to bottles with adifference circumference, the rotational angle of the bottles is held ata constant 90° during traversing the space or gap between conveyor belts4 and 45. For this purpose, one of the belts 41 can be positivelyengaged with the drive, not shown, for conveyor belts 4 and/or 45 whilethe other belt is regulated under the influence of a programmablecontroller, not shown, to adjust for different bottle diameters orcircumferences. Altering the ratio of transmission between the two beltscan be achieved simply by sending a signal to the controller by means ofa push button switch.

A sidewall inspection with two inspection stations 1 and 100 as in FIG.7 has the advantage of the spacing between the bottles in the bottlestream being kept small and the speed at which the bottles aretransported at a given power level is lower than is the case with aninspection of the total bottle sidewall with only one inspectionstation. This accomplishment results from the smaller angle which can beselected between beams 6 and 7. For example, the angle may be as littleas 60° since the bottle sidewall when passing one of the inspectionstations 1 and 100 does not need to be recorded with its fullcircumference. By way of the small angle, optical advantages areobtained during image recording. When only a single inspection stationis used for sidewall inspection, an angle of more than 100° is requiredbetween beams 6 and 7 for complete inspection of a bottle wall.

We claim:
 1. Apparatus for inspecting transilluminatable bottlescomprising:a source of light arranged on one side of a bottle that ispositioned for being transilluminated in at least three directions bylight emanating from said source, a single camera positioned at a sideopposite of the bottle from said source of light, said camera having anoptical axis that is directed to the axis of symmetry of a bottle thatis positioned for being inspected and the axis of symmetry of the bottleand said optical axis of the camera are intersected by a commonimaginary plane, first and second beams that contain images of thebottle respectively, after having passed through the bottle have theirpaths from the bottle to said camera defined, respectively, by first andsecond mirror systems where the mirror systems and the beams reflectedthereby are symmetrical to opposite sides of said plane, a third beamthat contains an image of the bottle after having passed through thebottle has its path from the bottle to said camera defined by a thirdmirror system arranged between said two mirror systems, each of saidfirst, second and third images that are contained in the beams definedby the respective mirror systems have a central axis which intersecteach other and said axis of symmetry of the bottle in a common point,and the lengths of said central axes of the beams from said common pointof intersection to said camera are equal.
 2. Apparatus according toclaim 1 including:a conveyor for conveying bottles in succession intosaid position for undergoing inspection, each of the beams having anaxis and all of the axes intersecting the axis of a bottle when saidbottle is positioned for undergoing inspection.
 3. Apparatus accordingto claim 1 wherein each of said beams (6, 7, 8) defined by said mirrorsystems have central axes (6', 7', 8') respectively, said central axesintersecting each other at a common point (10) within a bottlepositioned for being inspected, said central axes also intersecting theaxes of symmetry (11) of a bottle when it is positioned.
 4. Apparatusaccording to claim 1 wherein the said axes of the beams defined by saidmirror systems have equal lengths between 750 mm and 1500 mm. 5.Apparatus according to claim 1 wherein the lengths of said axes of thebeams defined by the mirror systems are all equal to substantially 1240mm.
 6. Apparatus according to claim 1 wherein said optical axis of saidcamera is substantially perpendicular to the direction in which thebottles are conveyed by said conveyor to the position for beinginspected.
 7. Apparatus according to claim 1 wherein said axes of thebeams that contain images of a bottle and are defined by said mirrorsystems are directed horizontally,said camera is arranged such that itsoptical axis is directed vertically and including:a mirror to which theaxes of all of said beams and the optical axis of the camera aredirected, said last named mirror being set in an angular attitudeappropriate for reflecting and changing the direction of the axes of thebeams and the axes of the camera from horizontal to vertical for theaxes of the beams and optical axis of the camera to be coincident at thecamera.
 8. Apparatus according to claim 1 wherein:one of said two beamsthat contains an image of the bottle defined by a mirror system isdefined by two cooperating mirrors (6a, 6b) disposed between the bottleand the camera and the other one of the two beams that contains an imageof the bottle is defined by two cooperating mirrors (7a, 7b) disposedbetween the bottle and the camera and arranged to reflect said two beamsaway from the axis of symmetry, the mirror arrangement in each of saidtwo systems that include mirrors (6a, 7a) reflecting beams (6, 7),respectively, in directions away from said plane of symmetry such thatsaid mirrors (6b and 7b) reflect said beams (6, 7), respectively, towardsaid plane of symmetry.
 9. Apparatus according to claim 8 wherein saidcamera is oriented such that its optical axis is directed horizontallyat a level above the level of a horizontal plane along which the bottleis moved to arrive at the position for being inspected.
 10. Apparatusaccording to claim 8 wherein each of said two beams have a central axis(6',7') and the angle between each axis and said plane of symmetry isbetween 45° and 80°.
 11. Apparatus according to claim 10 wherein saidangle is about 60°.
 12. Apparatus according to claim 8 including asecond camera (15) spaced from camera (3), the second camera arranged torecord a beam containing information about any one or all of thecontour, height and color of a bottle (5) positioned for inspection,theoptical axis of said second camera extending through a common point ofintersection of the axis of symmetry of the bottle the central axes(6',7',8') of the three beams (6,7,8) and the optical axis of the firstcamera (3).
 13. Apparatus according to claim 12 wherein the optical axis(12) of the sidewall inspection camera (3) is directed from the camera(3) to be intercepted and deflected by one mirror (8a) disposed on aline directed to said line of symmetry (11) and said mirror (8a)redirects said optical axis (12) laterally across the optical axis (17)of second camera (15) to another mirror (8b) whereby the optical axes(12, 17) of the sidewall inspection camera (3) and the second camera 15cross with an acute angle between them of about 15° to 35°. 14.Apparatus according to claim 13 wherein said acute angle is preferablyequal to about 25°.
 15. Apparatus according to claim 1 wherein:saidthird mirror system includes three mirrors (8c, 8b, 8a), one of saidmirrors (8c) in the third system is disposed substantially on said planeof symmetry for said defining of said beam containing a third image of abottle positioned for being inspected, said mirror (8c) is arranged toreflect said beam containing said third image in a direction away fromsaid plane of symmetry to a mirror (8b) positioned laterally away fromsaid plane of symmetry, and said mirror (8b) is arranged for reflectingsaid third image generally toward said plane of symmetry to a mirror(8a) positioned substantially on said plane of symmetry and arranged forreflecting said third beam along said plane into the camera. 16.Apparatus according to claim 15 wherein the optical axis of said camerais directed vertically and an additional mirror (13) is positioned forreceiving the three beams containing, respectively, an image of a bottlein inspection position, said additional mirror is arranged for changingthe direction of the beams from horizontal to vertical for the axes ofthe three beams to enter the camera coincident with the optical axis ofthe camera.
 17. Apparatus according to claim 1 including a base plate(19) on which the mirrors in said mirror systems are mounted forstanding, and a mirror positioning plate (21) arranged parallel to thebase plate, said positioning plate having slots into which the mirrorsextend.
 18. Apparatus according to any one of claims 15, 16, or 12wherein said camera (3) has a photosensitive image plate and individualimages defined by said mirrors are formed separately from each other andnext to each other on the image plate.
 19. Apparatus according to claim18 wherein said image plate is a charge coupled device matrix. 20.Bottle inspection machine having first and second inspection stations(1,100) each including structure defined in claims 9 or 15, bottles tobe inspected being conveyed through the first inspection station (1) andthen downstream through second inspection station (100), anda devicepositioned between station (1) and station (100) for turning bottlesabout their vertical axes through a predetermined angle before theyarrive at the second inspection station.
 21. A machine according toclaim 20 wherein said predetermined angle is about 90°.
 22. The machineaccording to claim 21 wherein said device is comprised of two beltshaving runs extending parallel to each other and translating in the samedirection for gripping a bottle between them, one belt having atranslational speed greater than the other to impart rotation to abottle.